Non-contacting actuator for rocker arm assembly latches

Patent metadata

Field	Value
Publication number	US-11002156-B2
Application number	US-201715432026-A
Country	US
Kind code	B2
Filing date	Feb 14, 2017
Priority date	Aug 18, 2015
Publication date	May 11, 2021
Grant date	May 11, 2021

Abstract

An internal combustion engine includes a valvetrain having a rocker arm assembly including a rocker arm on which a latch pin is mounted. An actuator for the latch pin, including an electromagnet, is mounted separately from the rocker arm. Therefore, the rocker arm is able to move independently from the electromagnet. The electromagnet is operative to cause the latch pin to actuate through magnetic flux following a magnetic circuit that passes through the rocker arm. Mounting the electromagnet apart from the rocker arm allows wires powering the electromagnet to be held in relatively static positions. The magnetic circuit is arranged to bring magnetic flux into the latch pin, or a co-acting part, within the volume of the rocker arm. This enables a compact design that is suitable for installation in engines where the available space under the valve cover may be very limited.

First claim

The invention claimed is:

1. A valvetrain for an internal combustion engine of a type that has a combustion chamber, a moveable valve having a seat formed in the combustion chamber, and a camshaft, comprising:
a rocker arm assembly comprising a rocker arm and a cam follower configured to engage a cam mounted on a camshaft as the camshaft rotates; and
a latch assembly comprising a latch pin that is mounted on the rocker arm and an actuator comprising an electromagnet that is mounted to a component of the engine other than the rocker arm;
wherein the latch pin is moveable between first and second positions;
the rocker arm is moveable independently from the electromagnet;
the actuator and the rocker arm assembly are positioned to make the electromagnet operable to cause the latch pin to translate between the first position and the second position; and
the actuator and the rocker arm assembly are positioned to make the electromagnet operable to cause the latch pin to translate between the first position and the second position through magnetic flux that passes through the rocker arm.

2. A valvetrain according to claim 1 , further comprising:
a pivot providing a fulcrum for the rocker arm;
wherein the electromagnet is mounted to the pivot.

3. An internal combustion engine comprising a valvetrain according to claim 1 , wherein the component of the engine to which the electromagnet is mounted is in a fixed position relative to the combustion chamber.

4. A valvetrain according to claim 1 , wherein:
the rocker arm has a load-bearing structure; and
the magnetic flux passes through that load-bearing structure.

5. A valvetrain according to claim 1 , wherein:
the rocker arm has a load-bearing structure that is paramagnetic; and
the magnetic flux passes through a pole piece fixed to that load-bearing structure.

6. A valvetrain according to claim 1 , wherein the rocker arm is formed primarily of low coercivity ferromagnetic material.

7. A valvetrain according to claim 1 , further comprising:
a pivot providing a fulcrum for the rocker arm;
wherein the pivot, the actuator, and the rocker arm assembly are structured and positioned to make the electromagnet operable to cause the latch pin to translate between the first position and the second position through magnetic flux that passes through both the pivot and the rocker arm.

8. A valvetrain according to claim 1 , wherein:
the magnetic flux considered in one of a North to South or South to North direction enters the latch pin directly from, or across only an air gap from, the rocker arm and leaves the latch pin crossing directly from or across only an air gap from the latch pin to a pole piece of the actuator; and
the rocker arm is moveable independently from the pole piece of the actuator.

9. A valvetrain according to claim 1 , wherein the latch pin completes a magnetic circuit that makes the electromagnet operative to cause the latch pin to translate between the first position and the second position such that if the latch were replaced by one made entirely from aluminum, the electromagnet would not be so operative.

10. A valvetrain according to claim 1 , wherein:
one of the first and second latch pin positions provides a configuration in which the rocker arm assembly is operative to actuate the moveable valve in response to rotation of the camshaft to produce a first valve lift profile; and
the other of the first and second latch pin positions provides a configuration in which the rocker arm assembly is operative to actuate the moveable valve in response to rotation of the camshaft to produce a second valve lift profile, which is distinct from the first valve lift profile, or the moveable valve is deactivated.

11. A valvetrain according to claim 1 , wherein:
the rocker arm assembly is operative to form a force transmission pathway between the cam and the moveable valve; and
the force transmission pathway includes the rocker arm.

12. An internal combustion engine comprising:
a valvetrain according to claim 1 ;
a cylinder head comprising a combustion chamber; and
a valve cover;
wherein parts of the internal combustion engine including the cylinder head and the valve cover enclose a space between the cylinder head and the valve cover;
one of the parts that encloses the space is closer to the latch pin than any of the other parts enclosing the space;
there is a shortest path between the latch pin and the closest of the plurality of parts;
a pole piece of the actuator is positioned along the shortest path.

13. An internal combustion engine according to claim 12 , wherein parts of the engine along the shortest path consist essentially of the pole piece of the actuator.

14. A valvetrain according to claim 1 , wherein when the rocker arm is not being lifted by any cam, a line passing through the latch pin and oriented in a direction along which the latch pin translates between its first and second positions does not pass through the electromagnet.

15. A valvetrain according to claim 1 , further comprising:
a second rocker arm assembly comprising a second rocker arm and a second latch assembly comprising a second latch pin mounted to the second rocker arm and moveable between first and second positions;
wherein the electromagnet is also operable to cause the second latch pin to translate between its first and second positions.

16. A valvetrain according to claim 1 , wherein:
the latch assembly is structured to stabilize the latch pin in the first position against perturbations toward the second position independently from the electromagnet; and
the latch assembly is structured to stabilize the latch pin in the second position against perturbations toward the first position independently from the electromagnet.

17. A valvetrain according to claim 16 , wherein:
the latch assembly further comprises a permanent magnet in a position such that:
with the latch pin in the first position, and absent any magnetic fields generated by the electromagnet, the permanent magnet is operative to stabilize the latch pin in the first position through magnetic flux following a first magnetic circuit; and
with the latch pin in the second position, and absent any magnetic fields generated by the electromagnet, the permanent magnet is operative to stabilize the latch pin in the second position through magnetic flux following a second magnetic circuit that is distinct from the first magnetic circuit.

18. A valvetrain according to claim 17 , wherein one of the first magnetic circuit and the second magnetic circuit passes through the actuator and the other does not.

19. A valvetrain according to claim 17 , wherein the permanent magnet is rigidly mounted in a fixed position on the rocker arm.

20. A valvetrain according to claim 17 , wherein the permanent magnet is mounted to the actuator.

21. A valvetrain according to claim 1 , wherein the latch pin passes through a hydraulic chamber formed by the rocker arm.

22. A method of manufacturing a valvetrain according to claim 1 , comprising:
manufacturing a rocker arm with a hydraulic chamber for receiving a hydraulically actuated latch pin; and
forming a valvetrain according to claim 1 using the manufactured rocker arm as the rocker arm of claim 1 and installing the latch pin of claim 1 through the hydraulic chamber.

23. A valvetrain for an internal combustion engine of a type that has a combustion chamber, a moveable valve having a seat formed in t

Assignees

• Eaton Corp
• Eaton Intelligent Power Ltd

Inventors

• Hughes Douglas Anthony
• Busdiecker Matthew Richard
• Stretch Dale Arden
• Juds Mark Allan

Classifications

• F01L13/0005

  Deactivating valves · CPC title

• F01L2001/186

  Split rocking arms, e.g. rocker arms having two articulated parts and means for varying the relative position of these parts or for selectively connecting the parts to move in unison · CPC title

• F01L1/185 Primary

  Overhead end-pivot rocking arms · CPC title

• F01L2820/03

  Auxiliary actuators · CPC title

• F01L2305/00

  Valve arrangements comprising rollers · CPC title